Numerous attempts have been made to formulate laundry detergent compositions which provide the good cleaning performance expected of them and which also have textile softening properties. Thus, attempts have been made to incorporate cationic textile softeners in anionic surfactant-based built detergent compositions employing various means of overcoming the natural antagonism between the anionic and cationic surfactant species. For instance, in British patent specification 1,518,529, detergent compositions are described comprising organic surfactant, builders, and in particulate form, a quaternary ammonium softener combined with a poorly watersoluble dispersion inhibitor which inhibits premature dispersion of the cationic in the wash liquor. Even in these compositions, some compromise between cleaning and softening effectiveness has to be accepted. Another approach to providing anionic detergent compositions with textile softening ability has been the use of smectite-type clays, as described in British patent specification 1,400,898. These compositions, although they clean well, require rather large contents of clay for effective softening, perhaps because the clay is not very efficiently deposited on the fabrics in the presence of anionic surfactants. Yet another approach to providing built detergent compositions with softening ability has been to employ nonionic surfactants instead of anionic with cationic softeners, and compositions of this type have been described in, for example, British patent specification No. 1,079,388, German Auslegeschrift No. 1,220,956 and U.S. Pat. No. 3,607,763. However, it is found that if enough nonionic surfactant is employed to provide good cleaning, it impairs the softening effect of the cationic softener, so that, once again, a compromise between cleaning and softening effectiveness must be accepted.
The use of clay together with a water insoluble cationic compound and an electrically conductive metal salt as a softening composition adapted for use with anionic, nonionic, zwitterionic and amphoteric surfactants has been described in British patent specification No. 1,483,627. The commonly assigned copending patent application U.S. Ser. No. 962452 filed Nov. 20, 1978, now U.S. Pat. No. 4,292,035, by Charles F. Battrell entitled "Fabric Softening Composition" describes granular textile softening compositions comprising a complex of a cationic softener and a smectite-type clay subsequently treated with an anionic surfactant. These compositions are intended primarily as rinse additives, where their cleaning performance is not of primary interest.
Recently it has been disclosed in British Patent specification No. 1,514,276 that certain tertiary amines with two long chain alkyl or alkenyl groups and one short chain alkyl group are effective fabric softeners in detergent compositions when chosen to have an isoelectric point in the pH range such that they are in nonionic (amine) form in a normal alkaline wash liquor and are more in cationic (salt) form at the lower pH of a rinse liquor, and so become substantive to fabrics. Use of amines of this class, amongst others, in detergent compositions has also been previously disclosed in British patent specification No. 1,286,054.